Birds frequently build nests on large man-made elevated structures such as chimneys, waterway navigation markers, outdoor sports lighting, and poles or towers used in the telecommunication and electric power industry. Raptors (Pandion haliaetus, Aquila spp., Falco spp.) corvids (Corvus spp.), and storks (Ciconiidae spp.) are birds with large wingspans that build large stick nest near the top of these tall, isolated structures which can cause human-bird conflicts and nest management issues. Large birds nesting on such structures present hazards to the birds themselves, structure integrity and equipment function, human health, and worker safety when accessing the structures for maintenance. Hazards include bird electrocution; structure equipment malfunction, failure or fire due to nest material obstruction with energized components or cooling vents; impact damage to equipment biohazard and slipping risk from human contact with bird excrement and impact injury to ascending tower climbers or pedestrians on the ground due to direct contact with birds or falling nest sticks.
The electric power industry has long experienced transmission outages, pole fires, bird electrocutions and other problems related to bird nesting on energized power poles and towers (APLIC 2006). Increasingly, communication towers and outdoor stadium lights have become more abundant on the landscape with a concomitant increase in raptors and other large birds using the tall structures for nesting, as the top of the poles and towers tend to incorporate horizontal platforms or structural members for mounting antennas or lamp fixtures that provide a wide, flat surface suitable for the birds to construct a large, stable nest.
Certain species of birds and their nests are protected from human disturbance by law. In cases where a protected species is actively occupying a nest on a man-made structure, access to the structure for equipment upgrades and maintenance is often limited until after the nesting season when the migratory breeding birds have departed the nest site for wintering grounds.
Certain species of nesting birds demonstrate extremely high attraction to a particular nest site. Due to this strong nest-site fidelity, even if a nest is removed or destroyed, the breeding bird will simply rebuild a new nest at the same location. Similarly, certain species will make persistent attempts to build a nest at a chosen site on man-made structures, even if the particular location does not provide optimal structural features for the birds to construct a nest. Due to this tenacious nest-building behavior, many nest deterrent or exclusion devices are often eventually defeated, especially if no alternate nesting structures is voluntarily provided nearby for the birds after the original nest is removed and an anti-nesting device installed. Physical barriers designed to discourage large birds from perching or roosting at night on tall structures often fail to prevent nest building (APLIC 2006).
Few anti-nesting devices are designed to discourage large birds from nesting on tall, human-made structures. There is a need for a practical working device that can be quickly and easily affixed to, adjusted, and retracted or removed from the structure for worker access to perform structure maintenance. Furthermore, the device should not injure or entrap the birds, present hazards to workers accessing the structures, or interfere with the function of equipment mounted on the structure.
For the foregoing reasons, there is a need for a practical working nest deterrent device that is strong, lightweight, and durable with minimal wind resistance and structure loading effect to discourage or exclude nest building attempts by birds with relatively long wingspans greater than 33 inches (84 centimeters) that commonly build large stick nests on tall, isolated structures (hawks, eagles, ospreys, owls, corvids, storks, etc.), which can be easily and quickly installed, retracted, and removed by single person while affording simple adjustability of the device to “fit” various types of structures without creating an entrapment hazard for birds, or interference with equipment mounted on the structure or worker access for equipment maintenance.